Imaging devices provide images which assist medical practitioners in positioning a needle to perform a wide range of procedures. These include such procedures as drainage, precision injections, biopsies, and ultrasonic imaging in performing, for example, amniocentesis, cordocentesis and transabdominal chorionic villus sampling.
While relatively broad, the imaging beam of such imaging devices is generally flat. To obtain a clear image of a needle as it is guided into a desired target area, it is often desirable for the needle to be positioned at an angle of approximately 45 degrees with respect to an axis of an imaging beam. However, it has often been difficult to maintain a needle within an imaging beam, particularly within the desired angle with respect to the imaging beam axis. Once the needle escapes this axis, it will not be seen by the imaging device, which may result in an inaccurate tissue sample or require reinsertion of the needle.
Various attempts have been made in the past to assist medical practitioners in maintaining a needle within an imaging beam axis. U.S. Pat. No. 5,758,650 issued Jun. 2, 1998 to Miller et al and U.S. Pat. No. 5,941,889 issued Aug. 24, 1999 to Cermak disclose needle guiding apparatuses adapted for attachment to a probe or transducer of an imaging device. While these devices provided some movement of the needle relative to the imaging device, such movement is severely limited. For example, to obtain a suitable entrant angle for the needle, the angle of the imaging device relative to the desired target area is severely restricted. As a result, the medical practitioner remains limited in properly positioning the needle prior to and during insertion, as well as properly positioning the imaging device once the needle is inserted into the desired target area.
U.S. Pat. No. 4,899,756 to Sonek discloses an articulated needle guide which is advantages for facilitating needle positioning during ultrasound imaging, yet further flexibility may be desired.
Accordingly, there is a continuing need for needle guide systems that allow proper positioning of a needle prior to and during insertion, while also allowing independent positioning of an imaging device with respect to the needle guide system once a needle is inserted into a desired target area. There is also a continuing need for methods for positioning a needle relative to an imaging device.